RESEARCH ARTICLE Enhanced performance of compact 2 × 2 antenna array with electromagnetic band-gap Muhannad K. Abdulhameed 1,2 | Mohd saari B. M. Isa 1 | Zahriladha Zakaria 1 | Imran M. Ibrahim 1 | Mowafak K. Mohsen 1,2 | Mothana L. Attiah 1 | Ahmed M. Dinar 1 1 Centre for Telecommunication Research and Innovation (CeTRI), Faculty of Electronic and Computer Engineering (FKeKK), Universiti Teknikal Malaysia Melaka (UTeM), Melaka, Malaysia 2 Ministry of Higher Education and Scientific Research, University of Kerbala, Kerbala, Iraq Correspondence Muhannad K. Abdulhameed, Faculty of Electronic and Computer Engineering (FKeKK), Universiti Teknikal Malaysia Melaka (UTeM), Melaka, Malaysia. Email: eng_mka@yahoo.com Abstract The side lobe effects cause the wastage of energy in antenna arrays. In this work, two types of electromag- netic band-gaps (EBGs) are used to diminish the side lobes in 2 × 2 Patch Antenna Array at 6 GHz through mushroom-like EBG and triple side slotted (TSS) EBG (TSSEBG). The proposed EBGs are placed on the top surface of the antenna array to eliminate undesired sur- face currents. The connecting vias in TSSEBG com- pared with the mushroom-like EBG structure is decreased from 392 to 92. Accordingly, an easy way in fabrication is guaranteed. The TSSEBG provided triple band gaps of frequencies compared with the structure of mushroom-like EBG that only had one. The TSSEBG is placed in a flexible structure, which is suit- able for antenna applications. The compact EBG and TSSEBG antenna arrays respectively demonstrate 13.77 and 14.68 dB gain, 14.2 and 15.3 dBi directiv- ity, −24 and − 28.5 dB side lobe, and 90.5% and 87% efficiency at the operating frequency of 6 GHz. KEYWORDS compact antenna array, electromagnetic band-gap, enhanced performance of the antenna, mushroom-like EBG, triple band gab EBG 1 | INTRODUCTION Microstrip antenna arrays have become highly popular in the field of antenna designing in recent decades. These antennas exhibit various characteristics, such as lightweight, low cost, compact, appropriate for integration with RF devices, and easy to fabricate. Antenna arrays can be used for increasing the total gain compared with single microstrip patch anten- nas and provide diversity reception. 1 Substantial radiating elements of the antenna array are contained in a regular arrangement to achieve a good radiation pattern. The antenna array construction aims to obtain a physical struc- ture that exhibits a perfect radiation pattern, whereas the directivity of a single radiating element presents many restrictions. 2 The excitation of the surface waves is one of the major restrictions of the antenna. This phenomenon is regarded as undesired waves, whereas radiated power is wasted in the dielectric substrate. Accordingly, antenna gain, directivity, and efficiency are diminished. In the last decades, many techniques were developed to decrease sur- face waves excited by printed antennas. Such techniques include placing an additional dielectric layer above the radi- ating element 3 or optimizing the radiating element shape. 4 An air cavity under a radiating element is drilled to obtain a low effective dielectric constant. 5 Step-like substrate, use thick substrate under the patch which helps to remain the compact size and bandwidth and use thin substrate around the patch which is beneficial to reduce the surface wave, this structure is just like a step. 6 However, bulky antenna size is resulted from adding additional layers. Use of costly sub- strate like an electromagnetic crystal substrate 7 is also reported. Different types of design techniques like slotted ground plane 8 and removal of substrate 9 are also reported but most of them provide gain of around (5-7) dBi. The compact design is effectively accomplished on high dielec- tric constant substrates. The surface waves become low as the dielectric constant increases. 10,11 Consequently, the bandwidth decreases, which can be solved by increasing the substrate thickness. 12,13 Electromagnetic band-gap (EBG), one of the most important technologies, was used to Received: 6 April 2019 DOI: 10.1002/mop.32092 Microw Opt Technol Lett. 2019;1–12. wileyonlinelibrary.com/journal/mop © 2019 Wiley Periodicals, Inc. 1